Interstitial cystitis (IC) is a debilitating, neurogenic bladder disease affecting primarily women with symptoms of pelvic pain, urinary frequency, and urgency. The etiology of IC is unknown, but chronic inflammation is associated with a large subset of patients. Mast cells are thought to play a central role in the bladder inflammation associated with IC, and we have recently shown that mast cells directly induce inflammatory responses in human urothetial cells that are mediated by tumor necrosis factor alpha (TNF). Although little is known about the role of TNF in bladder inflammation, anti-TNF therapy has proven efficacious in the treatment of other chronic inflammatory diseases including Crohn's disease and rheumatoid arthritis. Therefore, our hypothesis is that TNF is a major mediator of bladder inflammation induced by mast cells. To test this hypothesis, we have developed a culture model of mast cell-urothelial cell interactions and a mouse model of neurogenic cystitis using the neurotropic psuedorabies virus (PRV) that does not infect the bladder yet induces a centrally-mediated cystitis that mimics important aspects of IC including voiding dysfunction, involvement of mast ceils, and expression of inflammatory markers. In Aim 1, we will determine the TNF signaling requirements for urothelial inflammatory responses to primary murine mast cells in culture using specific antibodies and RNA interference technologies. In Aim 2, the role of mast cells and TNF in neurogenic cystitis will be determined by infusing wild type and TNF knockout mast cells into mast cell-deficient mice and then inducing cystitis with PRV. Similar experiments will also be performed with TNF receptor knockout mice. In Aim 3, the impact of chronic TNF exposure on bladder inflammation will be assessed using an existing transgenic mouse that expresses elevated systemic TNF and using mouse lines engineered to specifically express TNF in the urothelium. In Aim 4, the effects of anti-TNF therapy will be tested in both the neurogenic and chronic models of TNF-induced bladder inflammation using a TNF blocking antibody. Thus, this project will determine the role of TNF in bladder inflammation and examine a potential therapy for IC.